fix(extensions): reject non-mapping extension.yml config section

ConfigManager._get_extension_defaults() read extension.yml's config.defaults
via manifest_data.get("config", {}).get("defaults", {}) with no shape check
on the intermediate "config" value. A manifest with `config: []` or
`config: "oops"` (the top-level config.defaults field used by shipped
extensions like extensions/git/extension.yml, distinct from the already-
validated provides.config list) made the chained .get() raise a bare
AttributeError instead of degrading like every other malformed config
source in this class. The crash was silently swallowed by
should_execute_hook's blanket except, so a hook's `config.x is set`
condition permanently evaluated to False for the extension with no
diagnostic. Mirrors TestConfigManagerNonMappingYaml's existing coverage for
a non-mapping *root* of <id>-config.yml, one level deeper in the manifest's
own `config` section, which was previously unchecked.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FW9fAYsCBCAgdKWovtSyqt

Author: Noor-ul-ain001

src/specify_cli/extensions/__init__.py

@@ -4502,7 +4502,25 @@ def _get_extension_defaults(self) -> Dict[str, Any]:
             return {}
 
         manifest_data = self._load_yaml_config(manifest_path)
-        return manifest_data.get("config", {}).get("defaults", {})
+        # _load_yaml_config already coerces a non-mapping *root* to {}, but
+        # extension.yml's top-level 'config' key is unvalidated by
+        # ExtensionManifest (only 'provides.config' is checked there -- a
+        # different field). A manifest author's ``config: []`` or
+        # ``config: "oops"`` therefore reaches here as a dict whose 'config'
+        # value is a list/str, and the unguarded chained .get() raised a bare
+        # AttributeError ('list'/'str' object has no attribute 'get') instead
+        # of degrading like every other malformed-shape config source in this
+        # class. That crash was swallowed by should_execute_hook's blanket
+        # except, so a hook's 'config.x is set' condition silently and
+        # permanently evaluated to False for the extension -- mirroring the
+        # 'jira-config.yml' non-mapping-root case TestConfigManagerNonMappingYaml
+        # already covers for _get_project_config/_get_local_config, one level
+        # deeper in the manifest's own 'config' section.
+        config_section = manifest_data.get("config", {})
+        if not isinstance(config_section, dict):
+            return {}
+        defaults = config_section.get("defaults", {})
+        return defaults if isinstance(defaults, dict) else {}
 
     def _get_project_config(self) -> Dict[str, Any]:
         """Get project-level configuration.

tests/test_extensions.py

@@ -11060,6 +11060,68 @@ def test_hook_condition_returns_false_without_raising(self, tmp_path):
         assert executor._evaluate_condition("config.x is set", "jira") is False
 
 
+class TestConfigManagerNonMappingManifestConfigSection:
+    """A non-mapping `config:` section in extension.yml must not crash.
+
+    Distinct from TestConfigManagerNonMappingYaml above: that class covers a
+    malformed *root* of the project ``<id>-config.yml`` file, which
+    ``_load_yaml_config`` already coerces to ``{}``. Here the YAML root of
+    ``extension.yml`` is a well-formed mapping, but its own ``config:`` key
+    (read by ``_get_extension_defaults`` for ``config.defaults``) is given
+    the wrong shape -- e.g. a list instead of a mapping. That is one level
+    deeper than ``_load_yaml_config``'s guard and was previously unchecked.
+    """
+
+    def _make(self, tmp_path, config_yaml_body: str):
+        ext_dir = tmp_path / ".specify" / "extensions" / "jira"
+        ext_dir.mkdir(parents=True)
+        (ext_dir / "extension.yml").write_text(config_yaml_body, encoding="utf-8")
+        return ConfigManager(tmp_path, "jira")
+
+    def test_get_config_coerces_list_config_section(self, tmp_path):
+        """A list `config:` section previously raised AttributeError.
+
+        ``manifest_data.get("config", {}).get("defaults", {})`` assumed the
+        'config' value was already a mapping; a list value made the chained
+        `.get()` raise ``AttributeError: 'list' object has no attribute
+        'get'`` instead of degrading like every other malformed config
+        source in this class.
+        """
+        cm = self._make(tmp_path, "config:\n  - foo\n  - bar\n")
+        assert cm.get_config() == {}
+
+    def test_get_config_coerces_scalar_config_section(self, tmp_path):
+        cm = self._make(tmp_path, "config: just-a-string\n")
+        assert cm.get_config() == {}
+
+    def test_get_config_coerces_non_mapping_defaults(self, tmp_path):
+        """A non-mapping `config.defaults` value degrades to {} as well."""
+        cm = self._make(tmp_path, "config:\n  defaults:\n    - foo\n")
+        assert cm.get_config() == {}
+
+    def test_valid_defaults_still_load(self, tmp_path):
+        """The fix must not regress the well-formed shape."""
+        cm = self._make(
+            tmp_path,
+            "config:\n  defaults:\n    feature:\n      enabled: true\n",
+        )
+        assert cm.get_value("feature.enabled") is True
+
+    def test_hook_condition_returns_false_without_raising(self, tmp_path):
+        """`config.x is set` against a malformed manifest config must not raise.
+
+        Before the fix, _get_extension_defaults raised AttributeError and the
+        exception was swallowed by should_execute_hook, silently disabling
+        every config-based hook for the extension. Assert on
+        _evaluate_condition directly so the crash isn't masked.
+        """
+        ext_dir = tmp_path / ".specify" / "extensions" / "jira"
+        ext_dir.mkdir(parents=True)
+        (ext_dir / "extension.yml").write_text("config:\n  - foo\n", encoding="utf-8")
+        executor = HookExecutor(tmp_path)
+        assert executor._evaluate_condition("config.x is set", "jira") is False
+
+
 class TestConfigManagerEnvPrefixCollision:
     """Prefix-colliding env vars must not crash or clobber nested config."""